https://www.theguardian.com/science/202 ... stronomers
In this case, Mundell said, something appears to have prevented the neutron star “noticing how massive it is”. One possibility is that the star was spinning so fast and with such immense magnetic fields that its collapse was delayed – something like how water stays inside a tilted bucket if it is swung around fast enough.
“This is the first direct glimpse that we may have of a hypermassive spinning neutron star in nature,” said Mundell. “My hunch is we’ll be finding more of them.”
So, likely a "mundane" explanation. Though I'm now remembering stuff I've heard about hypothetical quark stars... Rommie?